Images generally consist of pixels, each of a single intensity and color, arranged on a microscopically square grid, building up to a much larger square or rectangular image. Alternative methods, using eg vectors or polygons rather than pixels as the underlying structural element, may be elsewhere referred to as “non raster.” In this specification, the term “non raster” refers to a different method of scanning pixels, rather than to non-pixel based graphic representations.
Under the prior art, the large rectangle of pixels has been scanned, or placed in sequence, by simply following straight horizontal lines from left to right across the image, then by retracing (or flyback) to the left again, to the start of the next line underneath the previous one, and so on, to the bottom of the image, then retracing to the top. This is the conventional raster scan. “Deflection” signals, or waveforms, one for horizontal and one for vertical, can define the precise trajectory of the raster scan. At the retraces, these signals become very steep, and the associated video signal, carrying the sequence of scanned pixel values, generally contains discontinuities at the retrace boundaries.
The tendency for discontinuities in the deflection signals at retrace, in the video signal at retrace, and also in the video signal while traversing the image, are either eliminated or much reduced by using M-Scan as specified herein, rather than the conventional raster scan.